Convection heating apparatus



P 1, 1964 H. E. WALKER CONVECTION HEATING APPARATUS Filed March 13, 1961INVENTOR. Ji /way L Tvizzse, ?4zm /Fazzm lrramvs k United States Patent3,147,368 CONVECTION IEATING APPARATUS Henry E. Walker, 17041 Burton St,Van Nuys, Calif. Filed Mar. 13, 1961, Ser. No. 95,173 Claims. (Cl.219-370) The present invention relates to a heating apparatus andparticularly to an electrically-controlled hot-air heater.

Baseboard heaters to be installed in a wall adjacent the floor arewidely employed in homes and business establishments. Often, these unitsconsist simply of an electrical resistance element mounted in a compactlowheight or low-profile natural convection housing. In operation, theheating element attains a high temperature and produces considerableheat which passes from the unit by radiation and natural convection.Generally, in order to get the required amount of heat for a given room,and in order to keep the wattage and temperature per lineal foot ofbaseboard within safe limits requires a great length of baseboard, oftenmore than is available. Such natural convection baseboard heaters havean indifferent circulation. That is, the heated air for the most partdrizzles straight up the walls above the heaters soiling the walls, andincreasing radiation losses.

One manner of avoiding these problems in a heater is to alter theprinciple of operation to forced convection. In such an altered unit,the air is moved over the heating element, then forced into the room orconfined space in which the unit is operated. The heated air is directedaway from the walls eliminating the soiling of the walls; and bydirecting the heat into the room, the high radiation losses which occurwhen the heated air drizzles straight up along the walls as in naturalconvection heaters are avoided. The forced air picks up the heat fromthe heating element much more efficiently than do natural convectioncurrents of air. Hence the heating element does not attain as high atemperature for a given wattage. The heating element in an apparatus ofthis type operates more effectively and at a lower temperature resultingin longer heating element life.

However, a forced-air convection heater would normally be quiteexpensive to manufacture in view of the cost and usual size of apparatusto move the air over the heating element without vibration or noise.Specifically, such an apparatus would require a blower to move air oversubstantially the entire heating element, a motor to drive the blower,and mounting fixtures for both of these devices. Additionally,forced-air systemsm often suifer deleterious vibration and stresses.Therefore, prior forced-air systems have often required a very rigidstructure to minimize vibration and noise. Furthermore, some form ofapparatus to control or regulate the operation of the motor and theheating element would also be necessary.

In general, an example of the present invention comprises a forced-airconvection baseboard type heater wherein air is circulated through ahousing over a heating element and exhausted to warm a room or otherconfined space. The air is circulated over the elongate heating elementby an elongate impeller positioned generally parallel to the heatingelement. The impeller is driven by a motor; and the combination of themotor and the im; peller is mounted in a floating arrangement to avoidthe necessity of precise alignment during installation and to permit theimpeller and motor constantly to accommodate themselves to substantiallyperfect alignment during operation increasing efficiency and decreasingmechanical vibrations thereby decreasing the noise of operation. Theoperation of the motor and the heating element is controlled by anelectrical thermostat which is placed in the path of air entering theunit from several intake vents 3,147,368 Patented Sept. 1, 1964 whichmay draw air from various locations in the room. The apparatus alsoincorporates structure tending to balance air pressures developedtherein to avoid vibration and noise.

An object of the present invention is to provide an improved baseboardheater.

Another object of the present invention is to provide a baseboard heaterutilizing an improved method of transferring heat from the heatingelement to the air thereby making it possible to have a much shorterbaseboard heater than heretofore possible with a baseboard heater of thesame capacity.

Still another object of the present invention is to provide such aforced-air convection heating unit which incorporatestemperature-sensitive means to control the operation of the unit.

A further object of the present invention is to provide an improved,substantially, noiseless convection heating apparatus which may beeconomically manufactured and easily installed.

One further object of the present invention is to provide an economicalelectrical convection heater wherein an air stream is directed over theentire length of an electrical heating element which is safely shielded.

Still one further object of the present invention is to provide aneconomical convection heater incorporating an elongate blower whichmoves a stream of air over substantially the entire length of aparallel-mounted heating element, which blower incorporates anadvantageous mounting apparatus.

These and other objects of the present invention will become apparentfrom a consideration of the following, taken in conjunction with thedrawings, wherein:

FIG. 1 is a perspective view of an apparatus constructed in accordancewith the present invention;

FIG. 2 is a front elevational view of the apparatus of FIG. 1 with thefront cover removed;

FIG. 3 is a vertical sectional view taken along line 33 of FIG. 2;

FIG. 4 is a perspective view of a portion of the apparatus shown in FIG.3; and

FIG. 5 is a fractional vertical sectional view of an alternative form ofa portion of an apparatus similar to that of FIG. 1.

Referring initially to FIG. 1, the heater is shown in a housing 10having a front panel 11 containing intake louvers 12 and exhaust louvers14, which constitute intake and exhaust ports respectively. Of course,various other intake and exhaust structures may be employed. The frontpanel 11 also supports a control knob 16 to turn the heater on and offand regulates the amount of heat provided through the louvers 14.

The'unit is energized through an electrical conductor 18 which may bevariously connected to a source of electrical power convenient theoperating location of the unit. The unit is normally afiixed on thefloor adjacent the wall supported by legs 22 formed of heat-insulatingmaterial. However, it may also be used as a wall-insert heater or as aportable unit, and moved to various locations as needed.

Considering the internal components of the apparatus, reference will nowbe made to FIG. 2. The heating element 26, in this example, comprises acoiled length of resistance wire which may extend in four lengths acrossthe unit and be supported by fibre insulation boards 28 to form anelongate structure. The boards may comprise asbestos solidified in abinder material or various other heat-resistant insulating materials.The boards 28 are held in position by brads 30 (FIG. 3) received througha duct member 32. The duct member 32 includes end sections 34 and 36(FIG. 2) by which it is aflixed to vertical spaced-apart brackets 38 and39 with screws 40 carrying spacers 42.

The duct member 32 is formed into a closed air passage by a horizontalvane 44 and a skirt 45 (FIG. 3) which are affixed between the verticalbrackets 38 and 39 for peeling air from the periphery of the impeller,see below. Therefore, these elements and the duct member 32 define anair passage between the intake louvers 12 and the exhaust louvers 14.

An elongate rotative impeller 46 (FIG. 4), substantially the length ofthe heating element 26, is mounted in the air passage defined by theduct 32 so as to be adjacent the intake louvers 12 and parallel to theelongate heating element 26.

The impeller (FIG. 4) includes elongate angularlyoffset blades 48supported in parallel relationship on spaceapart disks 50, 52 and 54.The disks 50, 52 and 54 concentrically receive a mounting shaft 56 whichis ailixed thereto. One end of the shaft 56 is coupled to a motor 60 bya coupling 62 while the other end is journalled into a bearing 64mounted in a support structure 66. The bearing 64 is supported on a stubshaft 68 which is in turn held in a yoke 70, that is pivotally afiixedto a bracket 72. Therefore, the bearing 64 is essentially floating andmay be variously aligned to accommodate angular deviations by the shaft56.

The mounting of the motor 60 is similarly flexible to accommodate theself-alignment of the impeller 46. Specifically, the motor 60 (FIG. 2)is pivotally-mounted on a bracket 74 which supports a yoke 76 carryingthe motor in a pivotal mounting 77.

The motor 60 and the resistance element 26 are energized under controlof a thermostat 78 and a thermostat control unit 80 which may comprise apotentiometer with a rotative shaft 81 including an on-off switch. Thetwo conductors 82 carried in the electrical cord 18 are joined through aseries circuit including the resistance element 26 and the control unit80. The motor 60 is then connected across a portion of the resistanceelement 26 by conductors 83. Thus, the current flow through theresistance element 26 is controlled by the control unit 80 in accordancewith the temperature sensed by the thermostat 78, and the setting of theshaft 81. The motor 60 is similarly energized, however a reducedpotential may be applied to the motor 60 by varying the portion of theresistance element across which the motor is connected. Therefore, themotor 60 need not be highly standardized and an inexpensive motor can beutilized with the proper operating voltage provided simply and easily byselectively connecting the motor across a proper portion of theresistance element 26. In the assembly of the illustrative embodiment ofthe invention, the housing may be stamped or otherwise formed of twoseparate sheet metal members 85 and 87 (FIG. 3) with the louvers formedin the front panel 11. Next, the brackets 38 and 39 (FIG. 2) may beaffixed to the back housing member 87 as by spot welding or riveting toprovide the support for affixing the duct member 32, the vane 44 and theskirt 45. The impeller and the resistance element may now be placed inparallel position and the impeller connected to the motor 60 andiournalled into the bearings 64. It is to be noted, that by reason ofthe mounting for the motor 60 and the support structure 66, the impelleris self-aligning and precise alignment procedures are avoided.

Next, the control unit 80 may be affixed to the bracket 38 and thethermostat 78 positioned at the intake of the apparatus and supported bya clamp 89. The electrical connections are then made between the controlunit 80 and the resistance element 26. Thereafter, the connection of themotor 60 across a portion of the resistance element is made, afterdetermining the best operating voltage for the motor, as by variouslycontacting the resistance element 26. The front housing member 85 maynow be placed on the unit, and fitted into clips 91 (FIG. 3).

In the operation of the heater as disclosed, the impeller 48 forces airover the thermostat 80, then around the heating element 26 to be heatedand expelled through the exhaust louvers 14. As the air is forcedthrough the passage by the blade 48, pressure fluctuations tend to buildup at the back of the heater between the impeller 46 and the heatingelement 26 (FIG. 3). Normally, this would tend to extend undesiredforces in the apparatus, producing vibration and noise. However, in thepresent system, a pressure variation is also developed on the skirt 45which tends to balance the pressure at the back of the heater. As aresult, unbalanced pressures do not develop and the apparatus operationis smooth and noiseless.

As air passes through the heater, the thermostat 78 receives it at anaverage temperature resulting from a combination of air from the severallouvers 12. As a result, the control unit operates to regulate thecurrent flow through the resistance element 26 in accordance with thecomposite temperature sensed by the thermostat 78 and the setting of therotative shaft 81 of the control unit 80 to which the knob 16 isaffixed. In general, this control by the thermostat means is exercisedto regulate the temperature in the room or restricted space. However, inaddition, the operation of the control unit provides considerable safetyin the operation of the heater. For example, if an obstacle, as a windowdrape, should restrict the air flow through the heater, the temperaturetherein would rise radically to cut off the electrical current flowthrough the resistance element 26 and thereby prevent the temperaturefrom becoming adequate to ignite the obstructing article. This safetyfeature in conjunction with the rather complete shielding provided theresistance element 28, and the lower operating temperature of theresistance element 28, results in a heater which is considerably saferthanprior similar devices.

Another important feature of the present invention,

resides in the manner of mounting the impeller 46 to permit economicalassembly and alignment, thereby avoiding expensive construction.

One other important feature of the present invention resides in theparallel-mounted blower and heating elements which enable a structurethat is simply and easily installed without removing sections ofbaseboard, yet capable of effectively converting electrical energy toheat at power rates of up to 1500 watts per lineal foot of heater.

Of course, other forms of various aspects of the present inventioninclude the structure shown in FIG. 5 which discloses a bearing assemblyattached to the bracket 39. The bearing assembly includes a ball 101seated in a half bearing plate 102 fastened to the bracket 39. Anopening in the plate 102 receives the other plate 104 which is spotwelded to the plate 102. Thus the plates are held in the opening 105 bybolts 106 to provide a flexible self aligning support for the shaft.

It should be noted that although particular embodiments of the inventionherein described are fully capable of providing the features andachieving the objects set forth, such embodiments are merelyillustrative and this invention is not to be limited to the details ofconstruction illustrated and described herein, except as defined by theappended claims.

What is claimed is:

1. A baseboard type circulating air heater to be operated from a sourceof electrical power comprising: an elongate housing defining an airpassage having air inlet and air outlet means; an elongate electricalresistance heating element positioned in said air passage; thermostatmeans for providing electrical control of said heating element, saidelement being connected with said thermostat means and adapted to beconnected to said source of electrical power whereby said thermostatmeans controls the power received by said heating element; an elongateimpeller positioned in said air passage parallel to said heating elementand for forcing air through said passage; a motor rigidly affixed tosaid impeller and being 5 electrically connected to said heating elementwhereby said motor is energized in coincidence with said heatingelement; and angularly flexible motor mounting means for supporting saidmotor in said housing.

2. Apparatus according to claim 1 wherein said motor is connected acrossa portion of said heating element whereby to be energized by a voltagereduced from the voltage of said power source.

3. A horizontally elongated, low-profile, forced air, electrical spaceheater comprising: an elongated thin-wall heater housing having afrontal face portion, and a horizontal length which is long compared toits height and horizontal depth; continuous air passage means in saidhousing including elongated intake and exhaust ports disposed in saidfrontal face portion for taking in and exhausting air of said space ingenerally the same direction, said ports being separated by not morethan a few inches; an electric motor-impeller unitary assemblyhorizontally mounted in said air passage means, said motorimpellerassembly including a motor, an elongated rotary impeller fixedlyconnected at one end to said motor and having an axis of rotation, apivotal, self aligning bearing means for rotatably supporting the otherend of said impeller, and self aligning pivotal means for pivotallysupporting said motor; and an electric heating means having an elongateconfiguration and being supported in said air passage meanssubstantially parallel to said axis, said heating means beingcharacterized in that it is capable of dissipating not less thanapproximately one thousand watts per lineal foot of said configuration.

4. The invention according to claim 3 in which said impeller includes:approximately six elongated impelling blades each disposed parallel tosaid axis and each being disposed substantially in a plane which isangularly ofifset from radial; and a plurality of light-weight,spaced-apart supporting disks connected to said blades in a supportingrelationship.

5. The invention according to claim 3 in which said air passage meansincludes a horizontally elongated, vertically short exhaust ductinterconnecting said impeller and said exhaust port within which aredisposed said elongate heating means, said duct including a rearradiation reflective wall and a forward air peeling skirt having anelongate edge disposed contiguously along the length of said impeller.

References Cited in the file of this patent UNITED STATES PATENTS835,570 Spencer Nov. 13, 1906 1,823,579 Anderson Sept. 15, 19311,950,768 Anderson Mar. 13, 1934 2,007,102 Wallace July 2, 19352,268,046 Marker et al Dec. 30, 1941 2,274,469 Booth Feb. 24, 19422,434,847 Hagen Jan. 20, 1948 2,451,926 Dallin Oct. 19, 1948 2,843,718Huck July 15, 1958 FOREIGN PATENTS 783,574 Great Britain Sept. 25, 1957

1. A BASEBOARD TYPE CIRCULATING AIR HEATER TO BE OPERATED FROM A SOURCEOF ELECTRICAL POWER COMPRISING: AN ELONGATE HOUSING DEFINING AN AIRPASSAGE HAVING AIR INLET AND AIR OUTLET MEANS; AN ELONGATE ELECTRICALRESISTANCE HEATING ELEMENT POSITIONED IN SAID AIR PASSAGE; THERMOSTATMEANS FOR PROVIDING ELECTRICAL CONTROL OF SAID HEATING ELEMENT, SAIDELEMENT BEING CONNECTED WITH SAID THERMOSTAT MEANS AND ADAPTED TO BECONNECTED TO SAID SOURCE OF ELECTRICAL POWER WHEREBY SAID THERMOSTATMEANS CONTROLS THE POWER RECEIVED BY SAID HEATING ELEMENT; AN ELONGATEIMPELLER POSITIONED IN SAID AIR PASSAGE PARALLEL TO SAID HEATING ELEMENTAND FOR FORCING AIR THROUGH SAID PASSAGE; A MOTOR RIGIDLY AFFIXED TOSAID IMPELLER AND BEING ELECTRICALLY CONNECTED TO SAID HEATING ELEMENTWHEREBY SAID MOTOR IS ENERGIZED IN COINCIDENCE WITH SAID HEATINGELEMENT; AND ANGULARLY FLEXIBLE MOTOR MOUNTING MEANS FOR SUPPORTING SAIDMOTOR IN SAID HOUSING.